The present invention relates generally to the dispensing of plastic fasteners of the type that are used, for example, to attach tags to articles of commerce and relates more particularly to needles used in fastener attaching tools for dispensing such fasteners.
Plastic fasteners of the type comprising an elongated flexible filament having a first cross-bar at one end and a second cross-bar (or other enlargement, such as a paddle or a knob) at the opposite end are well-known and have been widely used in a variety of applications, such as in the attachment of merchandise tags to articles of commerce, in the attachment of buttons to garments, in the lasting of shoes, and in various packaging applications. Typically, such plastic fasteners are mass-produced by molding processes into either one of two different types of assemblies. One such assembly, an example of which is disclosed in U.S. Pat. No. 3,103,666, inventor Bone, issued Sep. 17, 1963 (which patent is incorporated herein by reference), is a clip-type assembly, said clip comprising a plurality of fasteners, each such fastener comprising a flexible filament having a first cross-bar at one end thereof and a paddle or second cross-bar at the opposite end thereof The fasteners are arranged in a spaced, side-by-side orientation, with the respective first cross-bars parallel to one another and the respective paddles or second cross-bars parallel to one another, each of the first cross-bars being joined to a common, orthogonally-disposed runner bar by a severable connector. Adjacent second cross-bars or paddles also may be interconnected by severable connectors extending therebetween.
The aforementioned fastener clip is typically made by injection molding. Several commercial embodiments of the above-described fastener clip have been sold by the present assignee, Avery Dennison Corporation, as DENNISON(copyright) SWIFTACH(copyright) fastener clips.
A second type of fastener assembly, an example of which is disclosed in U.S. Pat. No. 4,533,076, inventor Bourque, issued Aug. 6, 1985 (which patent is incorporated herein by reference), is known as continuously connected fastener stock. In one type of continuously connected stock, the fasteners comprise a flexible filament having a cross-bar at one end thereof and a paddle (or second cross-bar) at the opposite end thereof, the respective cross-bars and paddles of successive fasteners being arranged end-to-end and being joined together by severable connectors. In another type of continuously connected fastener stock, the fastener stock is formed from two elongated and continuous side members coupled together by a plurality of equidistantly-spaced cross-links. Individual fasteners having an H-shape, often referred to as xe2x80x9cplastic staples,xe2x80x9d are dispensed from the fastener stock by cutting the side members at appropriate points between crosslinks.
Continuously connected fastener stock is typically made by a rotary extrusion process of the type disclosed in U.S. Pat. No. 4,462,784, inventor Russell, which issued Jul. 31, 1984, and which is incorporated herein by reference. Said rotary extrusion process typically involves the use of a rotating molding wheel whose periphery is provided with molding cavities that are complementary in shape to the desired fastener stock. To form fasteners, plastic is extruded into the cavities of the molding wheel, and a knife in substantially elliptical contact with the wheel is used to skive the molded plastic from the molding wheel. Following molding, the filament portions of the fasteners are typically stretched.
One consequence of the rotary extrusion process described above, particularly the skiving step thereof, is that the first cross-bar, the filament, and the second cross-bar (or paddle) are flat on one side thereof, with the flattened sides of the first cross-bar, the filament and the second cross-bar all lying in the same plane (see e.g., FIG. 1B of U.S. Pat. No. 4,462,784). The opposite sides of the first-cross bar, the filament, and the second cross-bar (or paddle) conform to the shapes of the molding cavities and are typically not flat. In the case of the first cross-bar, its opposite side is curved, thereby resulting in a cross-bar whose transverse cross-section has a shape resembling a semicircle or semi-ellipse.
Tools (often referred to as xe2x80x9ctagging gunsxe2x80x9d or xe2x80x9cfastener attaching toolsxe2x80x9d) for dispensing individual fasteners from continuously connected fastener stock above are known, examples of such tools being disclosed in the following U.S. patents, all of which are incorporated herein by reference: U.S. Pat. No. 4,039,078, inventor Bone, which issued Aug. 2, 1977; U.S. Pat. No. 5,433,366, inventors Deschenes et al., which issued Jul. 18, 1995; U.S. Pat. No. 4,121,487, inventor Bone, which issued Oct. 24, 1978; U.S. Pat. No. 5,320,269, inventors Deschenes et al., which issued Jun. 14, 1994; U.S. Pat. No. 4,955,475, inventors McCarthy et al., which issued Sep. 11, 1990; U.S. Pat. No. 4,456,161, inventor Russell, which issued Jun. 26, 1984; U.S. Pat. No. 5,024,365, inventor Bourque, which issued Jun. 18, 1991; and U.S. Pat. No. 4,998,661, inventors Deschenes et al., which issued Mar. 12, 1991.
Such tools typically comprise a needle, the needle typically including a stem portion. The stem portion typically is generally cylindrical in shape and has a longitudinally-extending, cylindrically-shaped bore adapted to receive the first cross-bar of a fastener. In addition, said stem portion also typically has a longitudinally-extending slot adapted to permit the filament portion of a fastener to extend therethrough while the first cross-bar of the fastener is disposed in the longitudinal bore of the stem portion. The stem portion also typically has a tip adapted for insertion into a desired article of commerce. The needle also may include a base portion, said base portion being attached to the rear of the stem portion and being adapted to be removably received in the tool. The stem portion and the base portion may be a unitary structure or, as is more often the case, the base portion is insert-molded onto the rear end of the stem portion.
Such tools also typically comprise an ejector rod for ejecting a first cross-bar from the needle and into the article of commerce and may also include a knife or similar severing means for cutting the severable connector between the first cross-bar being dispensed and its adjacent first cross-bar and feeding means for advancing the assembly of fasteners in the tool so as to align the forwardmost first cross-bar with the needle.
One problem that has been noted by the present inventor with respect to the dispensing of continuously connected fastener stock of the type described above using needles of the type described above is that, whereas the longitudinal bore and the longitudinal slot together have a symmetric transverse cross-sectional shape resembling an inverse lollipop (the longitudinal bore being circular in transverse cross-section, the longitudinal slot being rectangular in transverse cross-section and bisecting said longitudinal bore at the top thereof), the first cross-bar and the filament together have a xe2x80x9cdxe2x80x9d-shaped cross-section. As a result, a considerable portion of the transverse cross-section of the longitudinal bore is not occupied by any of the first cross-bar. Because the needle has a circular transverse cross-sectional shape, the effect of the bore being larger in cross-sectional shape than the fastener is that the needle has an outer width or diameter that is larger than that required by the fastener. Consequently, the needle creates an insertion hole in the article of commerce that is greater than that required by the fastener. Because it is desirable to minimize the size of the insertion hole (to minimize damage to the article), the outcome described above is undesirable.
In addition, because a considerable portion of the transverse cross-sectional area of the bore is not occupied by the cross-bar, proper engagement of the cross-bar by the ejector rod and proper translational movement of the cross-bar through the length of the bore due to action of the ejector rod is not always achieved. This results in occasional malfunctioning of the tool.
It is an object of the present invention to provide a new needle useful in the dispensing of plastic fasteners of the type having a flexible filament and a cross-bar at a first end thereof.
It is another object of the present invention to provide a needle as described above that overcomes at least some of the problems described herein with respect to existing needles.
According to one aspect of the invention, there is provided a needle useful in dispensing plastic fasteners of the type comprising a filament having a cross-bar at a first end thereof, said needle comprising a stem portion, said stem portion terminating in a tip at a front end thereof and being shaped to define a longitudinally-extending bore and a longitudinally-extending slot, said longitudinally-extending bore being dimensioned to receive said cross-bar, said longitudinally-extending slot being dimensioned to permit said filament to extend therethrough while said cross-bar is disposed within said longitudinally-extending bore, said longitudinally-extending bore having a first flat side, said longitudinally-extending slot having a first flat side, said first flat sides of said longitudinally-extending bore and said longitudinally-extending slot being coplanar.
As can readily be appreciated, the aforementioned needle is particularly well-suited for use with plastic fasteners wherein each of the filament and the cross-bar has a flat side and wherein said flat sides are coplanar. Examples of such fasteners include fasteners formed as part of continuously connected fastener stock made by rotary extrusion, such as plastic staples. Where fasteners of the aforementioned type are to be dispensed using the needle of the present invention, the longitudinally-extending bore and the longitudinally-extending slot of the stem portion of the needle preferably collectively have a xe2x80x9cdxe2x80x9d-shaped transverse cross-section, and the stem portion of the needle also preferably has a xe2x80x9cdxe2x80x9d-shaped transverse cross-section. Depending upon the transverse cross-sectional shape of the cross-bar, the longitudinally-extending bore may have a generally semi-elliptical transverse cross-sectional shape, a generally rectangular transverse cross-sectional shape or a like complementary transverse cross-sectional shape. The stem portion of the needle is preferably made of a boron/nickel alloy and is preferably fabricated using electroforming. The needle preferably further comprises a base portion, said base portion being insert-molded onto a rear end of said stem portion.
According to another aspect of the invention, there is provided a needle useful in dispensing plastic fasteners of the type comprising a filament having a cross-bar at a first end thereof, said needle comprising a stem portion, said stem portion terminating at a front end thereof in a tip, said stem portion having a longitudinally extending slotted bore, said longitudinally extending slotted bore having a flat side in transverse cross-section.
The aforementioned needle is also particularly well-suited for use with plastic staples and other plastic fasteners wherein each of the filament and the cross-bar has a flat side and wherein said flat sides are coplanar. The needle preferably further comprises a base portion, said base portion being insert-molded onto a rear end of the stem portion.
The present invention is also directed to a novel method of fabricating a needle well-suited for use in the dispensing of plastic fasteners of the type comprising a filament having a cross-bar at a first end thereof. According to one aspect of the present invention, such a method comprises the steps of (a) fabricating an unfinished stem portion, said fabricating step comprising electroforming a metal onto a master, said master having a xe2x80x9cdxe2x80x9d-shaped transverse cross-section, and then removing the master from the electroformed metal; and (b) finishing said unfinished stem portion, said finishing step comprising machining the unfinished stem portion to yield a finished stem portion, said finished stem portion terminating in a tip at a front end and being shaped to define a longitudinally-extending bore and a longitudinally-extending slot, said longitudinally-extending bore being shaped to receive said cross-bar, said longitudinally-extending slot being shaped to permit said filament to extend therethrough while said cross-bar is disposed within said longitudinally-extending bore, said longitudinally-extending bore and said longitudinally-extending slot collectively having a xe2x80x9cdxe2x80x9d-shaped transverse cross-section.
As can readily be appreciated, the needle made by the aforementioned method is particularly well-suited for use with plastic staples and other plastic fasteners wherein the filament and the cross-bar collectively have a generally xe2x80x9cdxe2x80x9d-shaped longitudinal cross-section (said cross-section being defined as being along the longitudinal axis of the filament and perpendicular to the longitudinal axis of the cross-bar). Preferably, the metal of the aforementioned method is a boron/nickel alloy, and said electroforming step preferably comprises depositing metal onto said master to a thickness of about 0.003-0.005 inch. The above-described method preferably further comprises insert-molding a base portion onto a rear end of the finished stem portion.
The present invention is also directed to a combination of a plastic fastener and a needle, said plastic fastener comprising a flexible filament having a cross-bar at a first end thereof, said cross-bar and said flexible filament collectively having a generally xe2x80x9cdxe2x80x9d-shaped longitudinal cross-section, said needle comprising a stem portion, said stem portion terminating in a tip at a front end thereof and being shaped to define a longitudinally-extending bore and a longitudinally-extending slot, said longitudinally-extending bore being dimensioned to receive said cross-bar, said longitudinally-extending slot being dimensioned to permit said flexible filament to extend therethrough while said cross-bar is disposed within said longitudinally-extending bore, said longitudinally-extending bore and said longitudinally-extending slot collectively having a generally xe2x80x9cdxe2x80x9d-shaped transverse cross-section.
Preferably, the fastener cross-bar of the aforementioned combination is generally semi-elliptical in transverse cross-sectional shape or is generally rectangular in transverse cross-sectional shape. In a particularly preferred embodiment, the cross-bar is generally rectangular in transverse cross-sectional shape and has a transverse cross-sectional height and a transverse cross-sectional width, said transverse cross-sectional height being greater than said transverse cross-sectional width and being parallel to the length of said flexible filament.
The present invention is also directed to a novel plastic fastener, said plastic fastener comprising a flexible filament having a cross-bar at a first end thereof, said cross-bar and said flexible filament collectively having a generally xe2x80x9cdxe2x80x9d-shaped cross-section taken along the length of said flexible filament and transverse to the length of said cross-bar, said cross-bar having a substantially rectangular cross-sectional shape with its transverse length being larger than its transverse width.
Additional objects, features, aspects and advantages of the present invention will be set forth, in part, in the description which follows and, in part, will be obvious from the description or may be learned by practice of the invention. In the description, reference is made to the accompanying drawings which form a part thereof and in which is shown by way of illustration specific embodiments for practicing the invention. These embodiments will be described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is best defined by the appended claims.